summary Prosthetic Joint Infections are serious complications of hip and knee arthroplasty and a common cause for revision arthroplasty. Diagnosis is multifaceted with elevated inflammatory markers, radiographic changes around the prosthesis and aspiration results all assisting with diagnosis. Treatment generally involves prolonged IV antibiotics and two-stage revision arthroplasty. Epidemiology incidence primary joint replacement 1-2% TKA vs. 0.3-1.3% THA revision joint replacement 5-6% TKA vs. 3-4% THA risk factors pre-operative active infection local cutaneous, subcutaneous, deep-tissue or joint infection systemic septicemia previous local surgery/prior local infection postoperative immune suppression immunosuppressant drugs anti-TNF agents (e.g. infliximab, etanercept, adalimumab, certolizumab, golimumab) antimetabolites (e.g leflunomide) corticosteroids immunosuppressive conditions (dysplasia or neoplasia) poorly controlled diabetes mellitus (HBA1c >7) chronic renal disease acute liver failure malnutrition (eg. albumin <3.5; total serum leukocytes <800) HIV (CD4 counts <400) inflammatory arthropathy rheumatoid arthritis psoriasis ankylosis spondylitis lifestyle factors morbid obesity smoking excessvice alcohol consumption intravenous drug use poor oral hygiene Etiology Pathophysiology most common bacterial organism include staphylococcus aureus staphylococcus epidermidis Coagulase-negative Staphylococcus (chronic infections) most common fungal pathogen Candida species (e.g. Candida albicans) Prophylaxis screening screen and optimize risk factors nasal mupirocin for decolonization of nasal MSSA/MRSA routine urine cutures NOT warranted pre-operatively, unless history or symptoms of UTI stop DMARDs 4-6 weeks prior to surgery revision joint replacement normalized ESR, CRP off antibiotics operatively pre-operative skin cleansing with antiseptic wash systemic antibiotics administered within 30 minutes to incision, and >10 minutes prior to tourniquet continued for 24 hours after surgery operative room vertical laminar airflow systems limit hospital personal OR traffic in-and-out of room post-operatively antibiotics prior to dental work is dependant on host risk factors Classification Time of onset Acute infection infection within 3-6 weeks from surgery CDC definition < 90 days from date of joint replacement biology usually confined to joint space no invasion into prosthetic-bone interface no biofilm production S. aureus commonly associated with acute THA PJIs Chronic infection infection more than 3-6 weeks from surgery CDC definition > 90 days from date of joint replacement biology biofilm created by all bacteria forms on implant within four weeks composition 15% cells and 85% polysaccharide layer (glycocalyx) glycocalyx allows biofilm to adhere to prosthesis and sealoff infection and protect bacteria from host immune system consequence no method exists to safety remove biofilm and eradication is difficult prosthetic explant indicated with infection >4 weeks due to biofilm infection has invaded prosthetic-bone interface S. epidermidis most common organism in chronic THA PJIs Source of infection Direct invasion sinus tract into joint capsule wound dehiscence Hematogenous infection infection in a longstanding infection-free joint secondary to another infection (eg. dental work, infected gallbladder) Presentation History may have history of the following recent or active bacteremia multiple local surgeries skin/epithelial tissue penetration (eg. IV drug use, colonoscopy, dental work, ulceration, wound complication) Symptoms persistent pain and stiffness at site of arthroplasty is associated with infection in >90% of patients acute onset with swelling, tenderness, and drainage chronic infections show pain and more subtle symptoms function deteriorates over time pain worsens over time Physical exam inspection sinus tract to the joint is a definite infection warmth, redness, or swelling low grade fever motion limited by pain and swelling Imaging Radiographs findings periosteal reaction scattered patches of osteolysis generalized bone resorption without implant wear transcortical sinus tracts implant loosening Bone scan modalitity Tc-99m (technetium) detects inflammation and In-111 (indium) detects leukocytes triple scan can differentiate infection from fracture or bone remodeling indications if infection is suspected, but cannot be confirmed by aspiration or blood work sensitivity and specificity 99% sensitivity and 30% to 40% specificity Positron emission tomography (PET) indication may help to identify areas of high metabolic activity using fluorinated glucose sensitivity and specificity 98% sensitivity and 98% specificity diagnostic criteria 2018 criteria for prosthetic joint infections as defined by Parvizi and associates Derived from 2011 MSIS; 98% sensitivity and 99.5% specificity for diagnosing PJI Major criteria (diagnosis can be made when 1 major criteria exist) sinus tract communicating with prosthesis pathogen isolated by culture from 2 separate tissue/fluid samples from the affected joint Minor criteria (preoperative diagnosis) The below scores are added together to determine: ≥6 = infected; 2-5= inconclusive; 0-1=not infected Serum Labs Elevated CRP (>10mg/L) or D-dimer (>860ng/mL) - 2 points Elevated ESR (>30mm/h) - 1 point Synovial Fluid Analysis Elevated synovial WBC (>3,000 cells/µl) or Leukocyte Esterase - 3 points Positive alpha-defensin - 3 points most sensitive and specific marker for PJI Elevated synovial PMN (>80%) - 2 points Elevated synovial CRP (>6.9mg/L) - 1 point Inconclusive (inconclusive preop score (2-5) or dry aspiration) Positive histology (>5 PMN per hpf in 5 hpf at x400 magnification (intraoperative frozen section of periprostehtic tissue) - 3 points Purulence in affected joint - 3 points Single positive culture - 2 points Preoperative score + intraoperative score combined Combined score ≥6 = infected; 4-5= inconclusive; 0-3= not infected Studies Labs Blood panel WBC not specific or sensitive ESR and CRP CRP physiology peaks 2-3 days after surgery returns to normal at 21 days (3 weeks) normal range acute (< 6 weeks from surgery) = <100 mg/L chronic (> 6 weeks from surgery)= <10 mg/L ESR physiology peaks 5-7 days after surgery returns to normal 90 days (3 months) normal range acute (< 6 weeks from surgery) = no consences chronic (> 6 weeks from surgery)= <30 mm/hr Serum interleukin-6 (IL-6, normal <10pg/mL) physiology peaks 8-12h after surgery returns to normal 48-72h after surgery (3 days) less commonly followed, but can monitor and follow the progress of infection outcomes has been shown to have the highest correlation with periprosthetic joint infection sensitivity 100%, specificity 95% false positives RA multiple sclerosis AIDS Paget's disease of bone Joint aspiration indications whenever there is a strong suspicion in order to confirm the diagnosis lab order request cell count and differential crystals gram stain cultures and specificity outcomes cell count and differential lowest serologic values suggestive of infection synovial WBC >1,100 cells/ul and PMN >64% in knees synovial WBC >27,800 cells/ul in the first 6 weeks after TKA suggestive of infection WBC >3,000 cells/ul and PMN >80% for hips WBC >4350 cells/ul and PMN >85% for MoM hips WBC >1166 cells/ul and PMN >64% for hip antibiotic spacers gram stain stain for bacteria in sample specificity > sensitivity positive test would be indicative of infection, however a negative test does not rule out infection repeat aspiration indicated in cases of inconclusive aspirate and peripheral lab data waiting two weeks for a repeat aspiration off antibiotics other tests alpha-defensin immunoassay test peptide released by neutrophils 100% sensitivity and 98% specificity for diagnosis of PJI sensitivity not affected by previous antibiotic administration leukocyte esterase colorimetric strip test Peri-operative analysis microbiology definitive diagnosis can be made if the same organism is obtained by repeat aspirations or at least 3 of 5 periprosthetic specimens obtained at surgery complications false-positive rate is 8% tissue sample better than swabs histology Intraoperative frozen section indications equivocal cases with elevated ESR and CRP or suspicion for infection sensitivity 85% and specificity 90% to 95% >5 PMNs/hpf x 5 hpf is probable for infection Treatment Nonoperative chronic suppressive antibiotic therapy indications unfit for surgery refuse surgery systemic spread and maintain joint motion with symptomatic relief outcomes 10% to 25% success rate of eradication 8% to 21% complication rate Operative polyethylene exchange with component retention, IV abx for 4-6 weeks indications acute infection (<3 weeks after surgery) acute hematogenous infection (weak literature, ideally <48-72hrs from symptom onset) techniques thorough tissue debridement and irrigation with large-volume of irrigant outcomes 50% to 55% success rate implants must be removed if reinfection documented Dependant of bacteria speciation one-stage replacement arthroplasty indications used more commonly in Europe for infected THA no sinus tract, healthy patient and soft tissue, no prolonged antibiotic use, no bone graft low-virulence organism with good antibiotic sensitivity technique use antibiotic-impregnated cement advantages lower cost and convenience with single procedure earlier mobility disadvantages higher risk of continued infection from residual microorganisms outcomes variable success of 75-100% two-stage replacement arthroplasty indications gold standard for an infected joint >4 weeks after arthroplasty must be medically fit for multiple surgeries requires adequate bone stock requires confirmation of microbial eradication benign clinical exam normal labs (WBC, ESR, and CRP) negative aspiration cultures obtain repeat cultures at least two weeks after planned antibiotic course has been completed techniques (see section below) prosthesis removal, antibiotic spacer, IV antibiotics for 4-6 weeks and delayed reconstruction outcomes bilateral TKA resection arthroplasty followed by 6 weeks of antibiotics and bilateral reimplantation has excellent results at 2-year follow-up early reimplantation within 2 weeks has 35% success rate delayed reimplantation >6 weeks has a 70-90% success rate cementless reimplantation in the hip has better outcomes than cemented resection arthroplasty indications poor bone and soft tissue quality recurrent infections with multi-drug resistant organisms medically unfit for multiple surgeries failure of multiple previous reimplantations elderly nonambulatory patients disadvantages short limb, poor function, and patient dissatisfaction technique remove all infected tissue and components with no subsequent reimplantation outcomes total knee success rate is 50% to 89% total hip success rate is 60% to 100% arthrodesis indications reimplantation is not feasible due to poor bone stock recurrent infections with virulent organisms outcomes 71% to 95% success rate with bony fusion and infection eradication amputation indications total knee infections recalcitrant to other options severe pain, soft tissue compromise, severe bone loss, or vascular damaged technique AKA Techniques Surgical debridement and polyethylene exchange debridement modular parts should be removed to remove fibrin layer between plastic and metal parts which acts as a nidus of infection polyethylene exchange be sure component available Two-stage replacement arthroplasty prosthetic explant surgical debridement must debride bone implant interface and soft tissues antibiotic spacer and IV antibiotics advantages of spacers reduce joint dead space, provide stabilty, and deliver high dose antibiotics disadvantages of spacers potential local or systemic allergic reactions increased chance of developing antibiotic-resistant organisms only heat-stable antibiotics can be added to cement static or dynamic (articulating) spacers can be used advantages of static spacers allow delivery of higher doses of antibiotics (not premade) better wound healing (no joint motion) advantages of articulating spacers decreased reimplantation exposure time better maintenance of joint space and motion decreased quad shortening better patient satisfaction both spacer types have equivalent functional outcomes and rate of infection recurrence spacer antibiotics each 40 g bag of cement should have 3 g of vancomycin and 4 g of tobramycin added gentamycin may be substituted for tobramycin elution of antibiotics depends on cement porosity, surface area (beads increase area), and antibiotic concentration must use heat stable antibiotics (vancomycin, tobramycin, gentamicin) IV antibiotics wait to administer intraoperatively until aspiration and cultures taken must be administered for 4 to 6 weeks after explant initial empiric regimen first-generation cephalosporin vancomycin (if any of the following are true) true allergic sensitivity to penicillin prior history of or documented exposure to MRSA unidentified organism fluconazole prefered for antifungal infections similar efficiacy with IV and oral formulations tailor the regimen based on microorganism and susceptibility testing reimplantation send tissue specimens for culture and frozen section pathology implant only if all preoperative and intraoperative measures are acceptable if intraoperative frozen section demonstrate acute inflammation, debride the wound, reapply cement spacer, and return later when using cement, use antibiotic-impregnated cement Local Antibiotics Properties active against the organism can be incorporated into delivery vehicle (PMMA) thermo stable (will not denature during exothermic polymerisation reaction) Choices aminoglycosides (gentimicin, tobramycin) effective against gram-negative bacilli synergistic against gram-positive cocci (Staphylococcus, Enterococcus) low risk of systemic toxicity Vancomycin effective against gram-positive cocci excellent elution properties Doses low dose = 2g antibiotics:40g of cement commercial antibiotic cement is low dose Cobalt G-HV (Biomet) Palacos R+G (Zimmer) Simplex P (Stryker) Cemex Genta (Exactech) SmartSet GMV (Depuy) VersaBone AB (Smith & Nephew) high dose ≥ 3.6g antibiotics:40g of cement highest doses without systemic toxicity 12.5g tobramycin:40g cement 10.5 vancomycin:40g cement practical dose vancomycin is 1g per vial, tobramycin is 1.2g per vial use 3g vanco and/or 3.6g tobramycin in 40g cement use extra liquid monomer (1.5-2 ampoules monomer : 1 bag cement) Elution properties rapid release in initial 24h followed by rapidly decline in release rate combination dosing (both tobramycin+vancomycin) increases release rate of antibiotics (more than if each were used alone) low levels at 5 weeks experimental models do NOT show difference in elution/concentrations in conventional wound closure vs negative-pressure wound therapy (NPWT) Mixing vacuum mixing removes air bubbles enhances mechanical properties may increase/decrease antibiotic elution rates hand mixing may lead to uneven distribution of antibiotics within cement and inconsistent release sequence of ingredients adding vancomycin powder after cement powder + liquid monomer mixed for 30s results in greater elution Newer techniques vancomycin powder directly into wounds (mostly in spine literature) antibiotic cement coated IM nails local antibiotics bonded to implant surface Complications Failure to eradicate infection poorer prognosis for 2-stage revision for methicillin-resistant organisms
QUESTIONS 1 of 71 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 Previous Next Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK (OBQ18.245) A 70-year-old man presents with chronic persistent right knee pain and erythema which has been present for 7 weeks after having undergone total knee arthroplasty (TKA) 7 years ago. He is referred after completing a course of oral antibiotics prescribed by his primary care physician, which did not improve his symptoms. His current radiograph is shown in Figure A. Laboratory testing reveals a serum C-reactive protein (CRP) of 50mg/L and an erythrocyte sedimentation rate (ESR) of 67 mm/h. Arthrocentesis is performed and reveals a synovial WBC of 1,500 WBC/uL, with 85% polymorphonuclear cells (PMNs), and negative final cultures. The alpha-defensin test is positive. What is the next best step? QID: 213141 FIGURES: A Type & Select Correct Answer 1 Repeat knee arthrocentesis after 2-week antibiotic holiday 10% (184/1770) 2 Revision of femoral component without antibiotic therapy 0% (5/1770) 3 One-stage revision arthroplasty with intravenous antibiotic therapy for 4-6 weeks 2% (42/1770) 4 Two-stage revision arthroplasty with intravenous antibiotic therapy for 4-6 weeks 86% (1527/1770) 5 Revision of tibial component without antibiotic therapy 0% (2/1770) L 1 Question Complexity A Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 4 Review Tested Concept Review Full Topic (OBQ18.127) A 62-year-old patient that underwent a right hip resurfacing arthroplasty 3 years ago develops worsening right hip pain over the past 6 months. The pain is present at all times, including at night. The patient does not walk with a Trendelenburg gait and does not have reproducible pain on hip examination. Laboratory inflammatory markers from 1 week ago were erythrocyte sedimentation rate of 66 mm/hr (reference <20 mm/hr), C-reactive protein of 22 mg/dL (reference <2.5 mg/dL), cobalt 0.5 µg/L (reference <0.7 µg/L), and chromium of 0.4 µg/L (reference <0.4 µg/L). Figure A demonstrates an AP radiograph of the pelvis. What is the next best step in management? QID: 213023 FIGURES: A Type & Select Correct Answer 1 Physical therapy 1% (10/1964) 2 Routine follow-up 0% (3/1964) 3 Arthrocentesis with synovial fluid analysis 83% (1629/1964) 4 2-stage revision 5% (100/1964) 5 Metal artifact reduction sequence MRI 10% (201/1964) N/A Question Complexity A Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 3 Review Tested Concept Review Full Topic (OBQ18.122) A 66-year-old patient that underwent a right total knee arthroplasty approximately 4 years ago presents with worsening right knee pain over the last 48 hours. The patient has a history of rheumatoid arthritis and recently underwent a dental procedure a week ago. Labs were significant for CRP of 212, ESR 105, and a WBC count of 11K. Aspiration yielded a milky-looking fluid with 55K nucleated cells with 97% PMN. Radiographs are shown in Figures A and B. What is the next best step? QID: 213018 FIGURES: A B Type & Select Correct Answer 1 Surgical intervention after cultures finalize 4% (63/1567) 2 Repeat aspiration of the knee and send for alpha-defensin 3% (47/1567) 3 Begin IV antibiotics and re-evaluate in 24-48 hours 2% (29/1567) 4 Proceed with surgical intervention now 89% (1394/1567) 5 IR guided drain placement 0% (1/1567) N/A Question Complexity A Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 4 Review Tested Concept Review Full Topic (OBQ18.123) A 63-year-old patient with a previous right TKA 4 years ago presents with worsening pain in the right knee. The patient reports that pain is worsened when starting physical activity, but is also present at night. Two weeks prior to presentation the patient was given a 1-week course of oral antibiotics for cellulitis affecting the right knee. Serum labs were significant for a CRP of 11 mg/L and an ESR of 35 mm/hr. Synovial fluid analysis revealed 1,000/µL nucleated cells with 85% PMNs and no evidence of crystals. Synovial cultures were negative for any bacterial or fungal growth. Synovial alpha-defensin is positive. Figures A and B are the AP and lateral radiographs of the right knee. The patient opts to undergo a revision total knee arthroplasty. What is the best management at this point? QID: 213019 FIGURES: A B Type & Select Correct Answer 1 Femoral component revision 1% (20/2147) 2 Tibial component revision 1% (21/2147) 3 Polyethylene component revision 5% (98/2147) 4 One-stage revision of both the femoral and tibial components 7% (147/2147) 5 Two-stage revision of both the femoral and tibial components 86% (1837/2147) L 1 Question Complexity A Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 5 Review Tested Concept Review Full Topic (OBQ18.64) A 68-year-old patient with diabetes progressively worsening left knee pain of 6 months duration. They underwent a left total knee arthroplasty 7 years ago. Figures A-B demonstrate the current radiographs. Aspiration of the left knee demonstrated 11,500 WBCs and 94% neutrophils. Aspiration cultures grew methicillin-resistant Staphylococcus aureus. What would be the best treatment approach for this patient? QID: 212960 FIGURES: A B Type & Select Correct Answer 1 Knee arthrodesis 0% (5/1849) 2 Long-term antibiotic suppression 0% (4/1849) 3 One-stage revision arthroplasty 0% (8/1849) 4 Two-stage revision arthroplasty 98% (1820/1849) 5 Above knee amputation 0% (0/1849) L 1 Question Complexity A Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 4 Review Tested Concept Review Full Topic (SBQ18BS.1) When investigating a periprosthetic hip or knee joint infection, which marker is most sensitive and specific for infection? QID: 211112 Type & Select Correct Answer 1 Alpha-defensin 63% (1285/2048) 2 Intraoperative frozen section 11% (221/2048) 3 Serum interleukin-6 (IL-6) 10% (201/2048) 4 C-reactive protein (CRP) 14% (278/2048) 5 Leukocyte esterase (LE) colorimetric strip test 2% (50/2048) L 3 Question Complexity A Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 1 Review Tested Concept Review Full Topic Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK (OBQ14.50.1) A 62-year-old woman presents to your clinic with knee pain and swelling 4 months after a primary TKA. Her initial recovery was uneventful, but she had a small pustule develop 6 weeks after surgery. An emergency room physician gave her 10 days of oral antibiotics for a "suture abscess" at that time. Since the ED visit, she notes worsening pain and persistent drainage. Figurs A represents a clinical photo from today's appointment. What is the next best step in management? QID: 212435 FIGURES: A Type & Select Correct Answer 1 Admit directly from clinic for I&D and polyethylene exchange 22% (459/2042) 2 Prescribe oral antibiotics and follow up in 2 weeks 0% (8/2042) 3 Aspirate the patient's knee and plan for surgery 76% (1553/2042) 4 Prescribe home health wound care 0% (4/2042) 5 Placement of a knee immobilizer and hold physical therapy for 2 weeks 0% (2/2042) L 3 Question Complexity A Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 3 Review Tested Concept Review Full Topic Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK (SBQ13HK.45.1) Which of the following most accurately lists the relative risk of periprosthetic joint infection (PJI) in total joint arthroplasty in order from lowest to highest risk? QID: 212341 Type & Select Correct Answer 1 Primary hip < primary knee < revision knee < revision hip 7% (150/2047) 2 Primary hip < primary knee < revision hip < revision knee 75% (1528/2047) 3 Primary hip < revision hip < primary knee < revision knee 5% (103/2047) 4 Primary knee < revision knee < primary hip < revision hip 3% (54/2047) 5 Primary knee < primary hip < revision knee < revision hip 10% (199/2047) L 4 Question Complexity C Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 2 Review Tested Concept Review Full Topic Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK (SBQ13HK.68.1) A 64-year-old male is 6 months out from left total knee arthroplasty. He has had at least two months of pain and swelling to the operative joint. In your initial workup, he is found to have a well-healed surgical incision, a serum CRP of 13mg/L and an ESR of 19mm/h. You perform arthrocentesis, which results in a negative alpha-defensin, synovial WBC of 1000 cells/µL, synovial PMNs of 90%, and synovial CRP of 4mg/L. What is the next best step in management? QID: 214225 Type & Select Correct Answer 1 Corticosteroid injection 13% (213/1622) 2 Proceed to OR for histologic examination 42% (675/1622) 3 Proceed with two stage revision 27% (445/1622) 4 Proceed with single stage polyethylene exchange with irrigation and debridement 13% (214/1622) 5 6 weeks of IV antibiotics 4% (66/1622) L 5 Question Complexity B Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 2 Review Tested Concept Review Full Topic Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK (OBQ13.234) A 60-year-old male with history of renal transplantation and previous intravenous drug abuse undergoes total knee arthroplasty. Two years later, he begins to have mild knee pain and low-grade swelling that persists for 10 months before he finally comes to the emergency room. Examination reveals no fever. Range of motion is 5 to 70 degrees. Erythrocyte sedimentation rate is 22mm/h, and C-reactive protein is 0.8mg/L. Knee aspiration reveals 12,000/mm3 nucleated cells with 76% neutrophils. Gram stain is negative and aerobic and anaerobic cultures are negative after 4 days in culture. His symptoms do not resolve after 5 days of empiric intravenous antibiotics and he is taken to the operating room for arthroscopic irrigation and debridement. Operative synovial tissue cultures are shown in Figure A. What is the best next step? QID: 4869 FIGURES: A Type & Select Correct Answer 1 Cessation of immunosuppressant medication, lifelong antimycobacterial suppression 1% (29/3694) 2 Open irrigation and debridement, implant retention and lifelong antifungal suppression 3% (125/3694) 3 Open irrigation and debridement, resection arthroplasty, antimycobacterial drugs for 6 to 12 months 9% (344/3694) 4 Open irrigation and debridement, single-stage exchange, antifungal drugs for 6 to 12 months 3% (96/3694) 5 Open irrigation and debridement, two-stage exchange, antifungal drugs for 6 to 12 months 83% (3063/3694) L 2 Question Complexity C Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 5 Review Tested Concept Review Full Topic Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK (OBQ12.263) Increasing the porosity of a cement spacer for an infected total knee arthroplasty leads to which of the following? QID: 4623 Type & Select Correct Answer 1 Increased strength 1% (32/3691) 2 Increased elution of antibiotics 90% (3330/3691) 3 Increased cement density 1% (29/3691) 4 Improved cement-prosthesis bonding 4% (165/3691) 5 Increased reinfection rate 3% (122/3691) L 1 Question Complexity B Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 2 Review Tested Concept Review Full Topic Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK (OBQ11.46) A 68-year-old woman underwent a right total knee arthroplasty 5 years ago and has increasing right knee pain over the past 2 months. Radiographs are seen in Figures A and B, respectively. Laboratory studies demonstrate a C-reactive protein of 10 mg/dL (normal < 2.0 mg/dL) and an erythrocyte sedimentation rate of 50 mm/h (normal < 20 mm/h). Knee aspiration shows white blood cell count of 3,400/mm3 with 90% polynuclear cells. The patient's gram stain and cultures are negative. What is the most appropriate next step in management? QID: 3469 FIGURES: A B C Type & Select Correct Answer 1 Irrigation and debridement with polyethylene spacer exchange 5% (191/4077) 2 One-stage revision 1% (57/4077) 3 Two-stage revision 91% (3695/4077) 4 One-stage revision with antibiotic impregnated cement 2% (93/4077) 5 One-stage revision with direct antibiotic infusion into knee joint via hickman catheter 0% (18/4077) L 1 Question Complexity A Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 3 Review Tested Concept Review Full Topic (OBQ11.195) A 50-year-old woman underwent cemented total knee arthroplasty 3 weeks ago. She reports that she has 1 week of drainage the size of a quarter on a gauze pad that she places over the incision three times daily. Her body mass index is 53 and her medical problems include hypertension and type 2 diabetes. Blood work shows a CRP of 1.1mg/L (normal 1-3mg/L). Knee aspiration yields WBC of 673 cells/mm(3) with 30% polymorphonucleocytes, and a negative gram stain. There is no surrounding erythema but there is a 1cm area at the inferior aspect of the wound that has a large amount of serous drainage able to be expressed. She has a painless range of motion is 0° to 117°. What would be the next most appropriate step in management? QID: 3618 Type & Select Correct Answer 1 Removal of all components with antibiotic spacer placement and staged revision 3% (87/3244) 2 One-stage irrigation and debridement with removal of components to a cementless prosthesis 1% (25/3244) 3 Empiric oral antibiotics for 4 weeks and steri-strips over the area of drainage 12% (378/3244) 4 Surgical exploration with debridement and possible polyethylene exchange 82% (2659/3244) 5 Bone scan and repeat aspiration with empiric intravenous antibiotics for 4 weeks 3% (83/3244) L 2 Question Complexity C Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 4 Review Tested Concept Review Full Topic (OBQ11.60) A 72-year-old man reports persistent, progressively worsening pain in his hip after undergoing a total hip arthroplasty 15 months ago. A current AP hip radiograph is shown in Figure A. What is the next most appropriate step in the care of this patient? QID: 3483 FIGURES: A Type & Select Correct Answer 1 IV Antibiotics 0% (8/3258) 2 Obtain serum metal ion values 1% (30/3258) 3 Obtain ESR, CRP, and WBC 95% (3104/3258) 4 Obtain CT and MRI of the hip 1% (44/3258) 5 Urgent debridement and component explantation 2% (59/3258) L 1 Question Complexity B Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 3 Review Tested Concept Review Full Topic Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK (OBQ10.54) A 64-year-old female underwent a total knee arthroplasty 4 years ago and has increasing pain for the past 6 months. Knee aspiration reveals 4,000 leukocytes with 80% polymorphonucleocytes and a 2-stage revision arthroplasty is planned. When comparing articulating cement spacers to static spacers following resection, all of the following are potential advantages of articulating spacers EXCEPT QID: 3142 Type & Select Correct Answer 1 Decreased quadriceps shortening 1% (36/3279) 2 Decreased rate of infection recurrence 84% (2766/3279) 3 Increased knee range of motion for duration of cement spacer implantation 4% (147/3279) 4 Better maintenance of joint space 2% (75/3279) 5 Decreased exposure time during reimplantation 7% (239/3279) L 2 Question Complexity C Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 2 Review Tested Concept Review Full Topic (OBQ10.147) A 65-year-old woman complains of worsening left knee pain 7 months following total knee arthroplasty. She reports good pain relief for the initial 5 months following surgery. Physical exam is notable for a stable knee with range of motion from 0-115 degrees. Radiographs are provided in Figures A and B. Which of the following is the most appropriate next step in management? QID: 3235 FIGURES: A B Type & Select Correct Answer 1 Nuclear bone scan 1% (18/3127) 2 One stage revision total knee arthroplasty 0% (15/3127) 3 Knee MRI 1% (17/3127) 4 CRP, ESR, WBC 96% (3001/3127) 5 Physical therapy with focus on range of motion and quadriceps strengthening 2% (61/3127) L 1 Question Complexity C Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 4 Review Tested Concept Review Full Topic Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK (OBQ09.45) A 65-year-old male presents with a painful right total knee arthroplasty, which was performed ten years ago. CRP is 15 mg/L. Knee aspiration reveals a purulent fluid with 3,100 WBC's with 83% PMN's. Culture results are pending. Which of the following is the best management option? QID: 2858 Type & Select Correct Answer 1 Physical therapy, ice, and follow-up evaluation in 2 weeks 4% (121/3153) 2 Repeat aspiration if cultures are positive 9% (288/3153) 3 Oral antibiotics 0% (8/3153) 4 Intravenous antibiotics 3% (105/3153) 5 Surgical explant of components 83% (2620/3153) L 3 Question Complexity A Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 5 Review Tested Concept Review Full Topic Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK (OBQ08.164) A 65-year-old male who had a total knee arthroplasty 8 years ago comes into the office with worsening knee pain. The orthopaedic surgeon is concerned about infection and aspirates the knee. Which of the following are the lowest laboratory values from a synovial aspirate suggestive of infection? QID: 550 Type & Select Correct Answer 1 WBC of 500 cells/ml and PMN 25% 1% (35/2841) 2 WBC of 1,000 cells/ml and PMN 25% 2% (64/2841) 3 WBC of 1,500 cells/ml and PMN 70% 82% (2338/2841) 4 WBC of 5,000 cells/ml and PMN 70% 10% (286/2841) 5 WBC of 25,000 cells/ml and PMN 70% 4% (106/2841) L 1 Question Complexity A Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 3 Review Tested Concept Review Full Topic Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK This is an AAOS Self Assessment Exam (SAE) question. Orthobullets was not involved in the editorial process and does not have the ability to alter the question. If you prefer to hide SAE questions, simply turn them off in your Learning Goals. (SAE07HK.92) A 68-year-old man with no significant medical history underwent a total knee arthroplasty 4 years ago. A radiograph is shown in Figure 55. He reports that he had no problems with the knee until 6 weeks ago when he noted the gradual onset of pain following a colonoscopy. Examination reveals a painful, swollen knee. Knee aspiration reveals a WBC count of 40,000/mm3. Management should consist of QID: 6052 FIGURES: A Type & Select Correct Answer 1 suppressive antibiotics. 2% (12/701) 2 open irrigation and debridement with polyethylene exchange. 4% (27/701) 3 one-stage resection arthroplasty and reimplantation. 3% (19/701) 4 two-stage resection arthroplasty and reimplantation. 90% (634/701) 5 arthroscopic irrigation and debridement. 0% (2/701) L 1 Question Complexity E Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 4 Review Tested Concept Review Full Topic This is an AAOS Self Assessment Exam (SAE) question. Orthobullets was not involved in the editorial process and does not have the ability to alter the question. If you prefer to hide SAE questions, simply turn them off in your Learning Goals. (SAE07HK.14) Antibiotic-loaded bone cement prostheses, such as that shown in Figure 8, are best created by using which of the following methods? QID: 5974 FIGURES: A Type & Select Correct Answer 1 Using commercially available antibiotic-loaded bone cement 4% (34/756) 2 Adding 0.5 g vancomycin to commercially available antibiotic-loaded bone cement 4% (30/756) 3 Adding 0.5 g tobramycin and 0.5 g vancomycin/unit of standard bone cement 7% (55/756) 4 Adding either 1.0 g vancomycin or 1.2 g tobramycin per 40 g of standard bone cement 37% (277/756) 5 Adding a minimum of 3.6 g tobramycin and 1.0 g vancomycin per 40 g of bone cement 47% (355/756) L 5 Question Complexity E Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 5 Review Tested Concept Review Full Topic (OBQ06.184) Which of the following total hip arthroplasty patients appropriately meets the criteria for a surgical debridement with isolated femoral head and polyethylene liner exchange? QID: 370 Type & Select Correct Answer 1 Prosthesis infection of 4 months duration 1% (27/3426) 2 Prosthesis infection 8 weeks following implantation 13% (432/3426) 3 Prosthesis infection 3 days following a systemic infection 83% (2848/3426) 4 Acetabular component loosening due to osteolysis 2% (75/3426) 5 Vancouver Type A periprosthetic fracture. 1% (31/3426) L 2 Question Complexity D Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 3 Review Tested Concept Review Full Topic (OBQ05.165) A 64-year-old woman with osteoarthritis underwent bilateral total knee replacement 3 years ago. Current radiographs are shown in Figure A. She reports a 3-month history of bilateral knee pain while at rest and increasing swelling in the knees. Her ESR and CRP are elevated and bilateral knee aspiration cultures reveal Staphylococcus aureus. What is the most likely outcome if the patient undergoes simultaneous, bilateral knee resection arthroplasty with cement spacer and a course of intravenous antibiotics? QID: 1051 FIGURES: A Type & Select Correct Answer 1 Prosthesis reimplantation with need for multiple surgical debridements at 2-year follow-up 5% (84/1672) 2 20% risk of above knee amputation 5% (78/1672) 3 Retention of antibiotic cement spacer and low chance of successful prosthesis reimplantation at 2-year follow-up 11% (177/1672) 4 50% rate of conversion to knee fusion following resection arthroplasty 5% (79/1672) 5 Successful prosthesis reimplantation at 2-year follow-up with less than 20% revision rate 75% (1247/1672) L 2 Question Complexity D Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 5 Review Tested Concept Review Full Topic (OBQ05.176) A 72-year-old male presents 2 years status post fixation of an impending pathologic right femur fracture due to metastatic renal cell carcinoma. He is minimally ambulatory due to pain. Despite radiation therapy, there has been progression of the lesion with extensive cortical bone loss, which is shown in Figure A. A proximal femoral replacement arthroplasty is performed without complications, and is demonstrated in Figure B. Which of the following is true regarding this patients post-operative course? QID: 1062 FIGURES: A B Type & Select Correct Answer 1 Deep prosthetic infection is the most common complication 52% (772/1476) 2 Mean Harris Hip score will likely not improve 5% (76/1476) 3 The patient will most likely continue to be minimally ambulatory 25% (362/1476) 4 Aseptic failure rate at 5 years is >50% 15% (225/1476) 5 Pre-operative radiation decreases the risk of infection post-operatively 2% (29/1476) L 4 Question Complexity D Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 1 Review Tested Concept Review Full Topic (OBQ05.235) A 67-year-old diabetic male presents 4 months status post right total knee arthroplasty (TKA) complaining of pain and stiffness for the last four weeks. A clinical photograph is shown in Figure A. Radiographs and a bone scan are shown in Figures B, C and D. Blood work shows an ESR of 14mm/hr (normal 0-12mm/hr) and a CRP of 2mg/L (normal 1-3mg/L). Knee aspiration yields WBC of 1000, 30% PMNs, and a negative gram stain. He finished a 14-day course of antibiotics prescribed to him by his primary care physician one week ago. Which of the following is the most appropriate next step in management? QID: 1121 FIGURES: A B C D Type & Select Correct Answer 1 Broad-spectrum, empiric oral antibiotics 2% (38/1730) 2 Repeat aspiration after one week 76% (1319/1730) 3 Irrigation and debridement of the right knee with a polyethylene liner exchange 7% (126/1730) 4 One-stage irrigation and debridement of the right knee with a component exchange 3% (58/1730) 5 Two-stage component removal, antibiotic spacer placement and subsequent revision 10% (181/1730) L 4 Question Complexity D Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 2 Review Tested Concept Review Full Topic (OBQ04.121) A 58-year-old man has significant pain and stiffness after undergoing right total knee arthoplasty 6 months ago. A current radiograph and bone scan are shown in Figures A and B. Labs show an ESR of 45mm/hr (normal 0-20) and a CRP of 13.5 mg/l(normal <10). Knee aspiration reveals a WBC count of 850 cells/mm(3) with 70% polymorphonuclear cells and no growth on culture. What is the next most appropriate step in management? QID: 1226 FIGURES: A B Type & Select Correct Answer 1 Two-stage component removal, antibiotic spacer placement and subsequent revision 20% (520/2660) 2 Observation with repeat ESR and CRP in one week 17% (453/2660) 3 Surgical debridement and polyethylene exchange only 4% (105/2660) 4 Repeat aspiration and culture 56% (1493/2660) 5 One-stage irrigation and debridement with exchange of all components 3% (76/2660) L 3 Question Complexity B Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 4 Review Tested Concept Review Full Topic
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